Looms, in particular ribbon looms of the type initially mentioned, are commonly known. Usually, the thread quantity to be transported for warp threads and/or weft threads in looms is supplied to the processing station either under negative control, to be precise tension control, or positively with a fixed mechanical setting. The disadvantage of a negative thread control is that the threads are subjected to load, particularly when threads of different quality and properties are used. In the case of rubber threads or other threads with elasticity, the negative control has to be adapted in each case, since the threads would otherwise be loaded by harmful stresses. By contrast, in the case of a positive mechanical control with a fixed setting, there is a disadvantage that the thread feeders can operate only with an adjustable constant pull which can be set only in terms of the weakest thread, with the result that the quality of the woven cloth is impaired.
EP 1 526 199 A discloses a loom with individually drivable thread transport devices which can be activated individually according to the pattern program, but control takes place as a function of tension, and individual overriding adaptation is not provided.
WO 2004/111322 discloses, for knitting machines, a mechanism with an electronic control device for controlling the weft thread introduction, which, on the basis of a pattern program regulates an individual thread transport for the knitted cloth to be produced. The knitting machine contains, furthermore, a correcting apparatus, by means of which an adjustable correcting factor can be superposed on the pattern-compatible functioning of components of the knitting machine.
WO-A-88/05089 discloses a method for regulating the warp thread tension in looms by regulating the drive speed of the warp beam and/or of the cloth beam by means of program-controlled stepping motors. However, a regulation of the weft thread tension or quantity is not disclosed, provided or suggested there. A similar method and a corresponding device for releasing and regulating the warp thread quantity is known from WO-A-91/05895, said warp thread quantity being calculated by means of a control arrangement, for example with a keyboard. However, here, too, a regulation of the weft thread tension or quantity is not disclosed, provided or suggested.